OK to Install Conduit Seal in Underground Pull Box?

[ericwg]

Hello Gang,

I have taken over a project in construction for which I did not do the design. In this design there is an above ground divided fuel tank; 1/2 gasoline, 1/2 diesel, with two separate fuel pumps/dispensers. The way it was designed, there is actually a pull box (concrete N30 Christy box), in the Unclassified Area, in between the source panelboard (inside an adjacent building) and the fuel tank (Classified Area). Schedule 40 PVC is spec'd for all underground conduit, thus, it will remain 24" below grade at all times and RMC 90° elbows will be used at both ends, adhering to 514.8, Exception No. 2. The question I have pertains to the conduit seal in the Unclassified Area. I am typically used to having the conduit stub up at the panelboard in RMC, or into a j-box related to the system, and installing the conduit seal just after the RMC stubs up above grade. I am not used to having the conduit run through a pull box first. Since this is the first point the conduit comes above grade in the Unclassified Area, is this not where the seal needs to be installed? Is it ok to install the conduit seal on the RMC right after it enters the pull box? If so, is it ok for the wiring to just exit the seal and have it transition to the conduit coming from the panelboard? Should a short nipple be installed on the top of the EYS to ensure none of the sealing compound leaks out? Or, is the pull box not a practical location for the EYS and the conduit needs to be re-routed to a more appropriate location to bring the RMC above grade and install the seal? Unfortunately, Article 514 provides a fair amount of detail, including exhibits, on what the conduit seal looks like in the Classified Area, but not the seal in the Unclassified Area.

Thanks so much for taking the time to read. I've attached a rough sketch to help illustrate the design and my questions.

 

[Another C10]

I've only done those maybe 3 or 4 times, although my non professional engineering brain would suggest don't use duct seal but maybe use the same process of separating the conductors packing the conduit with the wool and fill the last 1/2" with the resin. I cant imagine you need to add the fitting.

 

[ericwg]

I've only done those maybe 3 or 4 times, although my non professional engineering brain would suggest don't use duct seal but maybe use the same process of separating the conductors packing the conduit with the wool and fill the last 1/2" with the resin. I cant imagine you need to add the fitting.

Thanks for your reply. Just to be clear, I wasn't planning on using duct seal, just the EYS. Humor me, I am going to re-state your question just to make sure I am understanding you correctly. Are you suggesting I go through the same steps you normally would when you install an EYS, just not install the actual fitting? In other words, you're suggesting I separate out the conductors, push a wool dam inside the conduit, then just pour some sealing compound inside the conduit? I'm no AHJ, but if they asked to see the conduit seal on the unclassified side and I showed them that, my gut tells me they would not accept it. Admittedly, I'm not certain, which is why I'm here. But, reading 514.9(B) (from 2014 NEC), particularly the comment in the handbook (see snapshot), as well as what is shown in Exhibit 514.4, it really seems like I need a seal fitting. I'm just not sure about locating it in a pull box.

 

[xformer]

I've only done those maybe 3 or 4 times, although my non professional engineering brain would suggest don't use duct seal but maybe use the same process of separating the conductors packing the conduit with the wool and fill the last 1/2" with the resin. I cant imagine you need to add the fitting.

 

[Dsg319]

Hello Gang,

I have taken over a project in construction for which I did not do the design. In this design there is an above ground divided fuel tank; 1/2 gasoline, 1/2 diesel, with two separate fuel pumps/dispensers. The way it was designed, there is actually a pull box (concrete N30 Christy box), in the Unclassified Area, in between the source panelboard (inside an adjacent building) and the fuel tank (Classified Area). Schedule 40 PVC is spec'd for all underground conduit, thus, it will remain 24" below grade at all times and RMC 90° elbows will be used at both ends, adhering to 514.8, Exception No. 2. The question I have pertains to the conduit seal in the Unclassified Area. I am typically used to having the conduit stub up at the panelboard in RMC, or into a j-box related to the system, and installing the conduit seal just after the RMC stubs up above grade. I am not used to having the conduit run through a pull box first. Since this is the first point the conduit comes above grade in the Unclassified Area, is this not where the seal needs to be installed? Is it ok to install the conduit seal on the RMC right after it enters the pull box? If so, is it ok for the wiring to just exit the seal and have it transition to the conduit coming from the panelboard? Should a short nipple be installed on the top of the EYS to ensure none of the sealing compound leaks out? Or, is the pull box not a practical location for the EYS and the conduit needs to be re-routed to a more appropriate location to bring the RMC above grade and install the seal? Unfortunately, Article 514 provides a fair amount of detail, including exhibits, on what the conduit seal looks like in the Classified Area, but not the seal in the Unclassified Area.

Thanks so much for taking the time to read. I've attached a rough sketch to help illustrate the design and my questions.

I wouldn’t worry about having a nipple out of the top of the seal. I would just put a core grip (CGB) connector from the top.

 

[ericwg]

I wouldn’t worry about having a nipple out of the top of the seal. I would just put a core grip (CGB) connector from the top.

You're referring to a CGB fitting with multiple holes for all the conductors?

 

[Dsg319]

You're referring to a CGB fitting with multiple holes for all the conductors?

Yes, but honestly If that was to hard to find a single hole that will seal all the conductors up tight should work to keep water from getting the sealing compound and corroding it over time.

Your seal is placed in a underground pull box correct.

 

[ericwg]

Yes, but honestly If that was to hard to find a single hole that will seal all the conductors up tight should work to keep water from getting the sealing compound and corroding it over time.

Your seal is placed in a underground pull box correct.

I typically don't use a single hole CGB for multiple conductors. I would use a TC type cable, i.e. single jacket such that the CGB has a tight fit.

Yes, that's the main question I am asking...is it acceptable (if not common) to place an EYS inside an UG pull box? I haven't seen one in a PB before, but then again I don't do a ton of Hazardous area work.

 

[Dsg319]

I typically don't use a single hole CGB for multiple conductors. I would use a TC type cable, i.e. single jacket such that the CGB has a tight fit.

Yes, that's the main question I am asking...is it acceptable (if not common) to place an EYS inside an UG pull box? I haven't seen one in a PB before, but then again I don't do a ton of Hazardous area work.

I have never had one placed below grade in a pull box. Though I don’t know any thing prohibiting it. I use to work in the natural gas industry and the way most classifications was I worked around I only needed a boundary seal on one side or the other not both as the earth below grade was non-class.

 

[Another C10]

Humor me, I am going to re-state your question just to make sure I am understanding you correctly. Are you suggesting I go through the same steps you normally would when you install an EYS, just not install the actual fitting? In other words, you're suggesting I separate out the conductors, push a wool dam inside the conduit, then just pour some sealing compound inside the conduit? I'm no AHJ, but if they asked to see the conduit seal on the unclassified side and I showed them that, my gut tells me they would not accept it

Do your research, most importantly ask the person inspecting it, my idea may not be gold standard but the concept I'm pretty sure would accommodate the explosive concern. Innovation isn't necessarily wrong although there certainly may be a much better way. just sayin ..

I used that concept in the event the sweep coming into the pull box was within the bend not allowing for a more conventional method, fitting.
I certainly wouldn't attach it above ground as drawn.

 

[Ken_S]

Is there a reason for the concrete box and could it be omitted eliminating any possible issues with inspection or compliance?

 

[ericwg]

Is there a reason for the concrete box and could it be omitted eliminating any possible issues with inspection or compliance?

Before I answer your question, I do want to clarify that I just now realized how my initial sketch might be a little misleading. It makes it look like the EYS would be located above grade or half in/out of the pull box. That is not the case at all. It would be located completely inside the pull box. Now, to your question, the reason there's a concrete pull box at this location is because there are ~8-10 conduits passing through it. It's a normal electrical pull box. It just so happens to be the place where the conduit coming from my fuel pump (hazardous) area first opens up.

Since having posted this I have decided against putting the EYS in the pull box. I am going to pull that conduit back and re-direct it to stub up at the corner of an adjacent building. I'll have the Contractor install the EYS 18" or so AFG and from there run on up into an enclosure with equipment for the fuel system shut-off.

 

[quantum]

Hello Gang,

I have taken over a project in construction for which I did not do the design. In this design there is an above ground divided fuel tank; 1/2 gasoline, 1/2 diesel, with two separate fuel pumps/dispensers. The way it was designed, there is actually a pull box (concrete N30 Christy box), in the Unclassified Area, in between the source panelboard (inside an adjacent building) and the fuel tank (Classified Area). Schedule 40 PVC is spec'd for all underground conduit, thus, it will remain 24" below grade at all times and RMC 90° elbows will be used at both ends, adhering to 514.8, Exception No. 2. The question I have pertains to the conduit seal in the Unclassified Area. I am typically used to having the conduit stub up at the panelboard in RMC, or into a j-box related to the system, and installing the conduit seal just after the RMC stubs up above grade. I am not used to having the conduit run through a pull box first. Since this is the first point the conduit comes above grade in the Unclassified Area, is this not where the seal needs to be installed? Is it ok to install the conduit seal on the RMC right after it enters the pull box? If so, is it ok for the wiring to just exit the seal and have it transition to the conduit coming from the panelboard? Should a short nipple be installed on the top of the EYS to ensure none of the sealing compound leaks out? Or, is the pull box not a practical location for the EYS and the conduit needs to be re-routed to a more appropriate location to bring the RMC above grade and install the seal? Unfortunately, Article 514 provides a fair amount of detail, including exhibits, on what the conduit seal looks like in the Classified Area, but not the seal in the Unclassified Area.

Thanks so much for taking the time to read. I've attached a rough sketch to help illustrate the design and my questions.

Normally the C1D2 zone does not penetrate the ground as shown in your diagram, this is odd. I would expect to only require the one seal at the boundary on the left.

When you can't relocate an underground pull box outside of the hazardous zone, it's easier to use a Crouse ES Sealing hub inside of the underground pullbox than an EYD/EYS. Another option is Polywater Zip Seal for a non-explosion proof type seal. I don't have my code book next to me, but I do not believe the seals in your scenario need to be explosion proof.

 

[quantum]

I wouldn’t worry about having a nipple out of the top of the seal. I would just put a core grip (CGB) connector from the top.

Easier to use an ES Sealing Hub with a bushing and it won't need as much Chico. He can also substitute the Chico with Crouse TSC epoxy inside of the sealing hub.

 

[quantum]

You don't need 1 or 2 since you're not going in to a junction box, I'm assuming your box is open bottom.

 

[ericwg]

Normally the C1D2 zone does not penetrate the ground as shown in your diagram, this is odd. I would expect to only require the one seal at the boundary on the left.

When you can't relocate an underground pull box outside of the hazardous zone, it's easier to use a Crouse ES Sealing hub inside of the underground pullbox than an EYD/EYS. Another option is Polywater Zip Seal for a non-explosion proof type seal. I don't have my code book next to me, but I do not believe the seals in your scenario need to be explosion proof.

For clarification, the pull box in question is NOT located in the hazardous zone. It is in an unclassified area just like the aforementioned enclosure.

As far as your comment RE: only requiring one seal at the hazardous area, how do you interpret the section below from the Handbook (2017), right after Article 514.9(B). IMO this clearly states that a seal (of some kind) is required in the non-hazardous area at the panelboard. Granted, I am going through an enclosure and not making a direct connection to the panelboard, but I believe the same intent/requirement applies.

 

[ericwg]

Normally the C1D2 zone does not penetrate the ground as shown in your diagram, this is odd. I would expect to only require the one seal at the boundary on the left.

When you can't relocate an underground pull box outside of the hazardous zone, it's easier to use a Crouse ES Sealing hub inside of the underground pullbox than an EYD/EYS. Another option is Polywater Zip Seal for a non-explosion proof type seal. I don't have my code book next to me, but I do not believe the seals in your scenario need to be explosion proof.

Thanks for the reply. Interesting. I do see the ES sealing hub you're referring to on Eaton's website. I was going to ask how you keep the compound in place till it cures since I don't see anything in the Eaton instructions (see below). It says to knead it and then it is packed around the conductors. Does it harden up as it's kneaded so the typical fill isn't needed?

RE: your comment about the seal not needing to be explosion proof...I'm not sure the code does state it has to be explosion proof, however, the majority of the connectors I'm aware of that "fit the bill" all happen to be explosion proof. I'm not familiar with the Polywater Zip Seal you mentioned. I'll have to look that one up. Thanks again!

 

[ericwg]

You don't need 1 or 2 since you're not going in to a junction box, I'm assuming your box is open bottom.
View attachment 2560425

Well, that's not true anymore. If you take a look at my post from 4/23 you'll see that I decided to pull back the conduit that was going to enter the pull box I mentioned in my OP. Now I'm going to have it stub up at the corner of a building. My plan was to run it through an EYS then into a NEMA enclosure which contains a contactor to disconnect all fuel system power. There is a connection from this enclosure back to the source panelboard. I actually created a rough sketch of the setup which I'll paste it below. The EPO is the emergency power off (fuel system shutoff) button.

 

[quantum]

Well, that's not true anymore. If you take a look at my post from 4/23 you'll see that I decided to pull back the conduit that was going to enter the pull box I mentioned in my OP. Now I'm going to have it stub up at the corner of a building. My plan was to run it through an EYS then into a NEMA enclosure which contains a contactor to disconnect all fuel system power. There is a connection from this enclosure back to the source panelboard. I actually created a rough sketch of the setup which I'll paste it below. The EPO is the emergency power off (fuel system shutoff) button.

View attachment 2560428

You should really be using an EYD here so it can be drained. Grabbing my code book here shortly to respond to your other comment.

 

[ericwg]

You should really be using an EYD here so it can be drained. Grabbing my code book here shortly to respond to your other comment.

Hmmm, ok. When do you write back can you please explain why you feel I need an EYD vs an EYS. I don't have a ton of Hazardous area design and it typically applies to fuel pumps such as this. I've only used EYS fittings until now and have never had any issues. Appreciate your input on this.